1. Field of the Invention
The present invention relates to a backlight for a liquid crystal display which illuminates a liquid crystal cell by light emitted from a light source through a light-guiding plate, and to a liquid crystal display incorporating such a backlight.
2. Related Art
Among known backlights for a liquid crystal display in which light emitted from a light source (a fluorescent lamp such as a cold-cathode tube and a hot-cathode tube) is guided through a light-guiding plate and used for illumination, there is what is called a side lamp type backlight. Side lamp type backlights can be further classified as a reflection film type, in which light emitted from a light source is reflected by a reflection film and then introduced into a light-guiding plate, and a reflection plate type, in which light emitted from a light source is reflected by a reflection plate such as an aluminum plate and then introduced into a light-guiding plate. In both types, the light source, reflection film, etc. are attached to an end portion of the light-guiding plate.
In the above types of backlight, the light source (lamp) naturally needs to be replaced when it burns out (or reaches the end of its lifetime).
In such a case, it may be conceivable to replace the whole backlight as shown in FIG. 16. However, this method is wasteful and very costly because parts that need not be replaced are replaced together. Since a general liquid crystal display is wholly enclosed by a cover together with a backlight, the cover needs to be removed to replace the whole backlight, a cumbersome job. Furthermore, in replacing the whole backlight unit, dust is likely to be introduced between the liquid crystal cell and the light-guiding plate, causing some problems.
As shown in FIG. 16, there has been proposed a backlight for a liquid crystal display 80 in which a light source, a connector, a holder for holding those, and other parts constitute a single unit. It may be conceivable to replace this whole backlight unit 82. However, even in this case, parts that need not be replaced are replaced together. Therefore, this method is still wasteful and costly. Furthermore, the backlight unit 82 having the above configuration can be removed only in the direction along the light illumination surface (display surface of the liquid crystal cell) of the light-guiding plate 84, so it is necessary to provide a large space (a space along the direction of removing the backlight unit 82) for the purpose of removal. However, liquid crystal displays in which the density is being increased have no space margin. Furthermore, as above, a large opening is required for backlight replacement.
On the other hand, with the above configuration, the operation of replacing a single light source is dangerous for the ordinary user because the fluorescent tube itself is thin and easily broken. Furthermore, in the case of the reflection film type backlight, it is difficult for the ordinary user to replace the fluorescent tube singly, because attachment of the reflection plate as required in association with the fluorescent tube replacement requires a very special technique.